4 ms·

This sounds like the reason widening roads doesn't usually ease congestion. Which, really, can be summed up by my favorite Yogi Berra-ism "No one goes there no

This sounds like the reason widening roads doesn't usually ease congestion. Which, really, can be summed up by my favorite Yogi Berra-ism "No one goes there nowadays, it’s too crowded."

AnthonyMouse 10y ago
> This sounds like the reason widening roads doesn't usually ease congestion. It usually does actually. What is happening there is that you have different demand levels at different congestion levels. If you alleviate some congestion by widening the road then demand goes up. That is only a problem if the demand without congestion is higher than what even the wider road can handle. As long as the new road can handle the higher but still finite demand you get when there is no congestion, there is no problem. In other words, as long as you make the road wide enough for the congestion-free demand level to begin with, that doesn't happen.
- SilasX 10y ago
  That's technically true, but it assumes away the core, ever-present problems: - It may not be physically possible to add enough lanes to e.g. handle everyone who would ever want to commute into L.A. - Even if that road was correctly sized, it still has to dump the traffic into the next road, through the next intersection point. If you've increased the capacity of the freeway but none of smaller road networks that the traffic transitions to, you've just moved the bottleneck, not eliminated it. And that too may be physically impossible. In any practical situation car transportation efficiency does not scale well enough that you can avoid addressing the demand side.
  - AnthonyMouse 10y ago
    It isn't physically impossible to use eminent domain to seize all the property around the roads and then build 32 lane roads all over Los Angeles. That is a separate question from how stupid that is in comparison to the alternative of building higher density residential housing closer to where people work and with better mass transit. But if people don't want to do that either, you have to pick your poison. And there really are many cases (Los Angeles notwithstanding) where adding one lane isn't enough but adding two is and where that genuinely is the most reasonable option.
    - ricardobeat 10y ago
      The Wired article posted below has a pretty good rebuttal on those ideas.
    - CalRobert 10y ago
      Also, one thing that's often forgotten is that roads take up space. A lot of it. You make your roads bigger to accommodate more people, and all of your buildings wind up farther apart as a result. When buildings are farther apart you have to drive farther, meaning that everyone's journeys are longer, meaning more traffic... and on and on it goes. 14 percent of LA county (not just city!!) is parking. http://www.citylab.com/commute/2015/12/parking-los-angeles-maps-study/418593/ http://www.citylab.com/commute/2015/12/parking-los-angeles-m... I'm trying to find a better source, but at one point supposedly 59 percent of the central business district was car infrastructure (parking, roads, etc.) http://www.autolife.umd.umich.edu/Environment/E_Casestudy/E_casestudy2.htm http://www.autolife.umd.umich.edu/Environment/E_Casestudy/E_... I mean, at what point do you just build a 400 square mile skid pad with nothing else there just to "alleviate traffic"? Hell, that's practically what Orange County is already.
      - tim333 10y ago
        Gosh, 3.3 parking spaces per car (citilab article). That's be some space to free up when they're self driving.
        CalRobert 10y ago
        They're already empty most of the time, for what it's worth.
        SilasX 10y ago
        Assuming "parking spaces" include one's home space (like garage or reserved spot), 3 should be expected, at least: home, work, and wherever you're visiting.
        AnthonyMouse 10y ago
- roel_v 10y ago
  No, that is still only the short term new equilibrium. What happens is that roads with unused capacity (or at capacity, but acceptable congestion) get busier as activity increases around those roads, because of the excess capacity/low congestion. Of course it's more complex than just that; it heavily depends on the spatial relationship with job activity centers within commuting distance, social expectations, economic characteristics and many more, but the core tenet remains - adding roads is not a long term solution for congestion, spatial planning is.
ced_vdb 10y ago
all the cars on this new lane are not on another road adding to the traffic tho. Maybe it eases the traffic elsewhere There is a finite amount of cars after all
- nommm-nommm 10y ago
  https://www.wired.com/2014/06/wuwt-traffic-induced-demand/ https://www.wired.com/2014/06/wuwt-traffic-induced-demand/
closeparen 10y ago
Right, widening roads doesn't increase speeds for existing commuters, it serves more commuters at the same speed.

This sounds like the reason widening roads doesn't usually ease congestion. Which, really, can be summed up by my favorite Yogi Berra-ism "No one goes there nowadays, it’s too crowded."

AnthonyMouse 10y ago

> This sounds like the reason widening roads doesn't usually ease congestion. It usually does actually. What is happening there is that you have different demand levels at different congestion levels. If you alleviate some congestion by widening the road then demand goes up. That is only a problem if the demand without congestion is higher than what even the wider road can handle. As long as the new road can handle the higher but still finite demand you get when there is no congestion, there is no problem. In other words, as long as you make the road wide enough for the congestion-free demand level to begin with, that doesn't happen.

SilasX 10y ago
That's technically true, but it assumes away the core, ever-present problems: - It may not be physically possible to add enough lanes to e.g. handle everyone who would ever want to commute into L.A. - Even if that road was correctly sized, it still has to dump the traffic into the next road, through the next intersection point. If you've increased the capacity of the freeway but none of smaller road networks that the traffic transitions to, you've just moved the bottleneck, not eliminated it. And that too may be physically impossible. In any practical situation car transportation efficiency does not scale well enough that you can avoid addressing the demand side.
- AnthonyMouse 10y ago
  It isn't physically impossible to use eminent domain to seize all the property around the roads and then build 32 lane roads all over Los Angeles. That is a separate question from how stupid that is in comparison to the alternative of building higher density residential housing closer to where people work and with better mass transit. But if people don't want to do that either, you have to pick your poison. And there really are many cases (Los Angeles notwithstanding) where adding one lane isn't enough but adding two is and where that genuinely is the most reasonable option.
  - ricardobeat 10y ago
    The Wired article posted below has a pretty good rebuttal on those ideas.
  - CalRobert 10y ago
    Also, one thing that's often forgotten is that roads take up space. A lot of it. You make your roads bigger to accommodate more people, and all of your buildings wind up farther apart as a result. When buildings are farther apart you have to drive farther, meaning that everyone's journeys are longer, meaning more traffic... and on and on it goes. 14 percent of LA county (not just city!!) is parking. http://www.citylab.com/commute/2015/12/parking-los-angeles-maps-study/418593/ http://www.citylab.com/commute/2015/12/parking-los-angeles-m... I'm trying to find a better source, but at one point supposedly 59 percent of the central business district was car infrastructure (parking, roads, etc.) http://www.autolife.umd.umich.edu/Environment/E_Casestudy/E_casestudy2.htm http://www.autolife.umd.umich.edu/Environment/E_Casestudy/E_... I mean, at what point do you just build a 400 square mile skid pad with nothing else there just to "alleviate traffic"? Hell, that's practically what Orange County is already.
    - tim333 10y ago
      Gosh, 3.3 parking spaces per car (citilab article). That's be some space to free up when they're self driving.
      - CalRobert 10y ago
        They're already empty most of the time, for what it's worth.
      - SilasX 10y ago
        Assuming "parking spaces" include one's home space (like garage or reserved spot), 3 should be expected, at least: home, work, and wherever you're visiting.
        AnthonyMouse 10y ago
roel_v 10y ago
No, that is still only the short term new equilibrium. What happens is that roads with unused capacity (or at capacity, but acceptable congestion) get busier as activity increases around those roads, because of the excess capacity/low congestion. Of course it's more complex than just that; it heavily depends on the spatial relationship with job activity centers within commuting distance, social expectations, economic characteristics and many more, but the core tenet remains - adding roads is not a long term solution for congestion, spatial planning is.

ced_vdb 10y ago

all the cars on this new lane are not on another road adding to the traffic tho. Maybe it eases the traffic elsewhere There is a finite amount of cars after all

nommm-nommm 10y ago
https://www.wired.com/2014/06/wuwt-traffic-induced-demand/ https://www.wired.com/2014/06/wuwt-traffic-induced-demand/

closeparen 10y ago

Right, widening roads doesn't increase speeds for existing commuters, it serves more commuters at the same speed.